Tool joint



April 27, 1948. A. H. BELL TOOL JOINT Filed Sept. 18, 1943 INVENTOR dewf/ 5e BY g arm/(W5 fl U w W M g W i l w w g k m w w w L w Patented Apr.27, 1948 TOOL JOINT Alexander H. Bell, Los Angeles, Calif., assignor toContinental Oil Company, Ponca City, Okla, a corporation of DelawareApplication September 18, 1943, Serial No. 502,899

z (Ci.285--146) My invention relates to new and useful improvements intool joints for oil well drill pipe.

When drilling an'oil well the tool joints connecting the pipe sectionsof the drilling string are worn rapidly due to abrading or rubbing ofthe joints against the casing or the sides of the well bore. After thejoints become badlyworn the pipe cannot be used for drilling until thejoints have been rebuilt to substantially their of my improved drillpipe are internally upset to provide relatively thicker walls beneaththe threads. The crests of the threaded portions lie substantiallyinwardly from the plane of the outer pipe surface and the pipe tapersgradually from its outer surface to the crests. Moreover, the threadedportions, themselves,- are tapered more than conventional pipe threads.

The manner in which the threads are tapered and cut into the pipepermits an externally flush coupling to be screwed on the pipes. Theinternal upsets provide the requisite strength during drilling.Furthermore, I have found that the gradually increasing thickness ofpipe above the crests original dimensions. Since there are a great ofthe threads absorbs torque shocks more emmaany joints in aldrillingstring, dthe ttime, labor, ctifinltcllylr than a shoulder or a sharpincrease in an money nvo ved are consi era le. Badly t c ess.

,worn drill pipe is sometimes converted to liner or After a pipeembodying my invention becomes other type of oil well pipe requiring aflush or a too worn to be used as drill pipe the internallysubstantially flush external joint. Since drill pipe upset ends. can bedrilled out to substantially the is subjected to great torsionalstresses, the threads internal diameter of the pipe and the worn jointson conventional drilling pipe begin at the outside can be cut down tosubstantially the outside didiaisriigter or pipe and are mpelied aslfittle as amielter 9 f hthe pip .t glgsiclanibe donet 1lliuicgly andpos e so a a max mum c ness 0 metal eas y. econv er e r ppecan en e usedis provided beneath the joint to avoid twist-oils as liner or in anyother capacit Where a smoo h which occur most frequently at the crest orinner inn r ore o su stantial y unif rm diameter is end of the Joint.The taper of the threads must desirable and a flush or substantiallyflush exbe greater than in the case of ordinary pipe ternal joint isrequired. threads, however, in order that the stands of An importantobject of my invention is to pipe will stab" easily and make and break"provide a string of drill pipe that can be easilywithout thread damagewhile running in and out and inexpensivel converted and used as a liner01ft ltheuholtwao A ciiililventiofiial drifll pipe thread ortin anly1pthler capfiacity as on oil wellllpiptehwhtzrti e er es near e on s esur ace of the pipe ex erna us join s are required, w en e o to receivea coupling whose outer surface is flush joints become worn, therebysaving on the origiwith li;;hil;ehpipet or too near the iinner surfaceto ha] cost of the pipe and eliminating costly reperm e in ernal upsetto be rilled out withbuilding of the worn joints. out cutting into thethreads. Since the thread Other objects and advantages of myinvenconventionally employed for drill pipe will not tion will beapparent during the course of the accommodate a flush joint or coupling,it is necfollowing description. essary to cut of! and discard thethreaded ends In the drawing forming a part of this specifics and to outnew threads which allow an internal tion and wherein like numerals areemployed to fl s jo t to be efter t ew threads designate like partsthroughout the same, are cutthe worn tool joints can either be rebuiltFi 1 is a fragmentary longitudinal sectional fifpfiiiiiofi 125x222?Jfti? 3.211522 .0 F ii ring my a nven on;

and are expended in removing t threaded Fig. 2 is a fragmentarylongitudinal sectional ends or the Pipe and m cutting the newthreadsview showing a string of drill pipe converted to Moreover, thepipes are shortened by cutting oil 7 the ends and the discarded piecesrepresent waste make finer for on wens I have developed a arm pipehaving threaded In the drawing, wherein is shown "a preferred embodimentof my invention, attention is first ends of sufficient strength towithstand torsional air ct d t Fig 1 Th umeral m designates a stressesto which they are subjected and in which e e 1' k e I a 1 i the threadsare uniquely cut to accommodate 580mm 0 8 S rmg p either a tool joint oran externally flu h joint sections H) are arranged in longitudinalalignor coupling, More pecifically the end portions ment and their endsscrewed into tubular Joints or couplings H. The end portions lfla of thepipe sections are internally upset to provide a reater thickness of'metal beneath the threaded joint. However, the portions of increasedthickness extend well beyond the crests or inner ends portions Illa havebeen bored out to substantially the diameter of the intermediateportions lb and the couplings II have been cut down so that they aresubstantially flush with the outer surface of the pipe sections. InFig.2 1

have shown the drill pipe of Fig. 1 converted for use as liner or othersimilar pipe in anoil well, The joint I! is preferably a coarse casingthread,

the diameter at the crest of the thread being substantially less thanthe outside diameter oi the pipe. From its outside surface the pipetapers gradually as at 13 to the lesser diameter of the threads. Assuggested, this gradual taper prevents or materially reduces thepossibilityof twist-oil's since the torque Shocks are better absorbed bya gradually increasing thickness of pipe than by a shoulder or sharpincrease in thickness. I prefer that the threaded ends of the pipesections have a taper of from 1 /4 inches to 1 inches per foot. This isenough taper'to cause the stands of pipe to stab easily and to "make andbreak without thread damage. Moreover, this degree of taper centrallylocates the joint so that'the internal upset of the pipe can be drilledout and the tool joint cut down without destroying any of the threads.If the tapered joint is not located in the center of the minal portionsof said coupling being axially tapered complementary to the taperedouter sursection it is mechanically impossible to either bore out theinternal upset or to turn down the tool joint or coupling without,destroying all or part of the threads.

I contemplate using drill pipe of the 'type shown in Fig. 1 until thecouplings ll become so worn that they must be either rebuilt orreplaced, and then converting the worn drillpipe to use as a liner asshown in Fig. 2. Assuggested; I further'contemplate using the converteddrill pipe in any other capacity where external flush or substantiallyflushjoi'nts are required. Of course, the lite of a drilling stringvaries with the type of formations through which the 'well bore isdrilled and the treatment and care the string is given during drillingoperatiofis. As an example, in'one instance a 1500 foot section of drillpipe was used to millions ,sections an internal diameter substantiallythe same .as conventional line is provided and by reducing the diameterof couplings ll ample clearance for the liner is assured.

From the foregoing it is apparent that I have 70 threads.

file of this, patent:

' .4 accompmhfi th objects of my invention. 1 have reduced the pitch"diameter of the conventional drill pipe'but have tapered the threadsufllciently so that it is suitable for toolloint use and, inaddition,have uniquely located the thread centrally in the section so that it canbe retained for use as a' pipe coupling in casing or liner where flushjoint pipe is needed by turning'oif theoutside of the tool Joint andborin out the inside of the upset. -It is to be understood that the formof the invention herewith" shown and described is to be taken'as apreferred example of the same and that variouschanges-in the size, shapeand arrangement of parts may be resorted to without departingfrom thespirit of my invention or the scope of the appended claims.

Having'thus described'my invention, I claim: 1. A tool joint for oilwell drill pipes comprising aligning pipe sections, the end portions ofthe pipe sections being internally upset; a tubular collar or couplingsurrounding and threa'dedly connected to theadjacent end portions of thepipe sections, the' threaded joints between the respective pipes andcouplings being tapered toward the ends of the pipe and positionedentirely between the inner and outer walls of the 'pipe sections, thepitch diameter of the narrow outer ends of the Joints being sunlclentlygreater than the inside diameter of th Pipe so that' the'internai upsetscan be bored out without cutting into the threads, the pitch diameter ofthe joints at their crests or inner ends' beingsubstantially less thanthe outside diameter of the pipe,'said pipe tapering'gradually from its"outer surface to the crests of the threads, and the internal terfaces onthe ends of the pipe and of such diameter as'to' engage the taperedoutersurfaces on the ends of the pipes.

2. In a joint device of the character described,

a drill-pipe convertible into'a well casing section and'having an endportion internally'upset and outer endpbeing sufliclently-greater thanthe. in-' 'side'diameter of'thepipe that the internal upset can be boredout without cutting into the Bani.

nnmnnucns crrnn are of record in the The following references UNITEDSTATES PATENTS I Number v Name Date 4 1,364,478 Boyd-ct a1.v Jan. 4,1921 1,889,867 Montgomery .Dec. 6, 1932 1,889,870 Montgomery 'Dec. 6,1932 2,308,056 Evans Jan.-12, 1943 FOREIGN PA'I'ENTS Number Country Date380,450 Great Britain Sept. 13, 1932 392,827 Great Britain May 25, 1933

